Raheem Sterling had chances to put the game to bed and City were made to pay.

United were rejuvenated after the break as Paul Pogba scored twice in 97 seconds.

And Chris Smalling completed the incredible turnaround as he tapped home unmarked.

David De Gea made a number of fine saves late on as tempers boiled over.

Here are six talking points from the Etihad.

City celebrate their opener (Image: REX/Shutterstock)

Kompany wheels away in delight (Image: Getty Images Europe)

(Image: REUTERS)

1. Kompany brings back memories of 2012

There were shades of 2012 when Vincent Kompany put City ahead with a bullet header in the 25 minute.

The City skipper scored at the same end with a carbon copy header in City's 1-0 derby win over United six years ago, a result that swung the title race in their favour that year.

It was fitting it was Kompany who set the Blues on their way to the title once again, only for Guardiola's men to squander their 2-0 lead and throw away what looked a nailed-on win to clinch the title.

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2. Pogba sends message to Pep

Paul Pogba found himself at the centre of the pre-derby build-up when Guardiola claimed he had been offered the United's record £89m signing in January by the player's agent, Mino Raiola.

If Guardiola's claim was designed to mess with Pogba's head, it had the desired effect, with the midfielder abject in the first-half. But Pogba was a man transformed after the break, scoring twice in quick succession to get United back on level terms before they went on to win against all the odds.

Gundogan plays the ball under pressure from Pogba (Image: REUTERS)

3. Sterling so wasteful

Guardiola has improved Raheem Sterling's finishing this season, with the winger having plundered 21 goals this season.

But Sterling reverted to type on two occasions in the first-half, failing to hit the target when clean through with only David De Gea to beat. Had Sterling shown more composure, City would have gone in at half-time 4-0 up, piling the humiliation on United.

As it was, his double miss proved costly, as United came from 2-0 down to produce a quite remarkable comeback to win 3-2.

City fans celebrate wildly after Kompany's goal (Image: John Peters)

4. Sanchez proves class

Alexis Sanchez has struggled to produce his best form for United since his much-heralded January move from Arsenal, but he stepped up to the plate here to provide a timely reminder of his enduring quality.

His delivery to Ander Herrera led to Pogba's opener, then Sanchez himself picked out the France star with an exquisite ball as he claimed his second to level the score. And Sanchez was the architect of United's third, his dead-ball delivery converted by Chris Smalling.

Gundogan adds a second (Image: Getty Images Europe)

5. Young lucky with poor challenge inside the box

City should have had a penalty after five minutes, when Ashley Young slipped and used his outstretched left arm to divert the ball from the path of Sterling, who was waiting to turn it into the net.

And City were denied another penalty in the 77 minute when Young went in recklessly on Sergio Aguero as he prepared to shoot. Fernandinho tried to exact revenge by hacking down Jesse Lingard, which led to ugly scenes involving players from both sides.

Danilo challenges Pogba (Image: Action Images via Reuters)

6. De Gea wonder save seals victory

David De Gea provided compelling proof of why he is the world's best goalkeeper with a stunning match-winning save to deny Sergio Aguero what would have been a certain goal in the 89th minute.

Aguero rose to power a header goalwards, but De gea somehow managed to reach up and tip the header over for a quite astounding save.